Prosocial behavior in middle childhood is linked to educational and occupational success and resiliency to antisocial behavior in adolescence and adulthood;thus, it is critical to better understand processes through which prosocial behavior may be encouraged in middle childhood. In the proposed research, two key areas are integrated to illuminate the development of prosocial behavior in middle childhood. First, communication about the reasons for children's behavior is important. The burgeoning literature on attributional feedback demonstrates strong influences of person-focused feedback (e.g., child's success is due to intelligence) and process-focused feedback (e.g., child's success is due to effort or strategic choices) on children's academic and task performance. Attributional feedback, however, has been less studied in relation to social behavior in general and prosocial behavior in particular. A critical methodological obstacle in applying the literature on attributional feedback to prosocial behavior is providing a challenge for children to surmount. Pilot research yielded a novel, ecologically-valid paradigm for assessing children's change in prosocial behavior following an interpersonal challenge. Thus, this research will be the first to examine how attributional feedback about children's prosocial behavior influences subsequent prosocial behavior following interpersonal challenge. The second key area to be integrated regards children's self-concept. The developmental shift in middle childhood is especially important, as children's self-concept transforms at this time to encompass traits. For some children, being kind or empathetic may become centrally important to their sense of self, whereas for others, it will not. Because attributions about traits are presumed to affect children's behavior by focusing attention on the self, children's prosocial self-concept may alter the impact of person-focused feedback on children's prosocial behavior. This research will be the first to address whether children's self-concept moderates the effect of attributional feedback on prosocial behavior. These aims will be addressed through experimental manipulation and multi-method measurement of children's self-concept and prosocial behavior with 102 nine- and ten-year-old children. This research will advance the science of child development by (a) resolving contrasting theoretical explanations about how children's reflection on their own traits influences their behavior and (b) shedding light on the processes through which prosocial behavior can be encouraged. Novel methodological paradigms will result. Use of experimental methods high in ecological validity strengthens the applicability of results for developmental, social, clinical, and educational psychology. PUBLIC HEALTH RELEVANCE: Given the increased emphasis on character education in public schools, and the recent positive psychology movement toward understanding how character strengths such as altruism may promote resilience and well- being, findings from the proposed research may have important direct relevance for educational practice and for intervention and prevention programs aimed at promoting children's socio-emotional development.